This application intends to identify the sources of individual variation (genetic and environmental influences) in health among African-American twin pairs aged 65 years and older. The assertion is made that knowledge about African-Americans allows greater insight into the role of environment and genetics in aging among the greater populace. Using a twin-sibling research design, this research addresses 1) specification of the sources of genetic and environmental influences on health in older African-Americans, 2) proportions of genetic and environmental influences accounting for covariance between health and personality, cognition, mental health, and social factors, and 3) specification of the differences in the similarity of health of twins compared to other siblings. To address these questions, there are four (sic) major objectives: (1) identify a sample of 400 paris of same-sex aged African-American twins and 200 siblings of the aged twins who reside in North and South Carolina and Virginia from a national population-based registry developed by the Black Elderly Twins Study; (2) perform in-person interviews of African-American twins and their siblings to assess the following dimensions of later life: cognition, mental health, physical health, personality, and social variables; and (3) access Medicare records on health care utilization.